Heat the oil in a large skillet over medium heat. Lightly toast the fennel seed in the hot oil until fragrant, 2 to 3 minutes. Add the carrots, pear, sweet potato, russet potato, mushrooms, curry powder, and turmeric to the fennel seed; cook and stir until everything is evenly coated in oil, 2 to 3 minutes. Pour the vegetable broth over the mixture. Stir the rice, flax seed, bay leaves, and parsley into the broth; bring the mixture to a boil, reduce heat to low, and simmer until the rice and vegetables are very tender, about 30 minutes.

Pour the soup into a blender, filling the pitcher no more than halfway. Hold the lid of the blender in place with a towel and carefully start the blender, using a few quick pulses to get the mixture moving before leaving it on to puree. Puree in batches until smooth and pour into a clean pot and return to heat.

Stir the lemon juice and white pepper into the mixture; cook until thoroughly reheated, about 5 minutes.